Method of carrying out metallurgical operations



May 5, 1925.

C. STEENSTRUP METHOD oF CARRYING OUT METALLURGICAL OPERATIONS OriginalFiled Sept. 25 1922 )L/ f. His At/orfwey.

Ivm/enten Chr-sam teerwsCTu M Patented May 5, 1925.

UNITED STATES PATENT OFFICE.

CHRISTIAN STEENSTRUP, OF SCHENECTA'DY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

METHOD OF CARRYING OUT METALLURGICAL. OPERATIONS.

Original application led September 23, 1922, Serial No. 590,007. Dividedand this application filed' August 13, 1924. Serial No. 731,861.

To all whom it may concern:

Be it known that I, CHRISTIAN S'rnnN- s'rRUr, a citizen of the UnitedStates, residing at Schenectady, in the county of Schenectady, State ofNew York, have invented certain new and useful Improvements in Methodsof Carrying Out Metallurgical Operations, of which the following is aspecification.

My invention relates to a method of carrying out metallurgicaloperations, and has for its object a simple, reliable, and etlicientmethod of carrying out various metallurgical operations in an enclosedspace.

This application is a division of my copending application, Serial No.590,007, filed Sept. 23, 1922.

Certain metallurgical operations for example, the uniting of metallicparts by fusion of copper or other metals, are carried out in thepresence of a reducing gas, in closed furnaces which are wellheat-insulated. After the operation is completed, a long time, sometimesseveral days, has been required to cool the furnace and its contents andhence the output of the fur-r nace has been very seriously restrictedand the cost of the product has been correspondingly increased.

A slow rate of cooling in some cases is disadvantageous in its effectupon the work. For example, when uniting metal parts by fused copper,silver, or the like, in hydrogen, it is desirable to cool the'workrapidly, after the union has been completed, particularly from thehighest temperature down to a point where further alloying or otherundesired action stops.

In accordance with my invention, greater efficiency and economy ofoperation of gasfilled furnaces is obtained by utilizing the same gaswhich is necessary to the metal- 'lurgical operation as a coolingmedium. This is accomplished by establishing a circulation of said gasthrough the furnace and a cooling means after the heat-treating processhas been completed. As a. result of my invention a complete operationcan be carried out in a large industrial furnace in less than one-fourthof the time formerly reyquired.

"As a further consequence of my invention an improved product can beproduced, parheating means, as for example, electric resistors 2. Inletand outlet pipes 3 and 1, respectively, are provided for admitting andcarrying away gas, as for example, hydrogen. During the heatingoperation or working period of the furnace, sufficient gas is suppliedto provide a slight excess so as to produce a low pressure in theconfined workcontaining space or chamber. l/Vhen operating with acombustible gas, such as hydrogen, some gas is permitted to burn at theoutlet pipe 4f to indicate whether or not a suitable pressure exists in`the apparatus.

'lhe cover 5 of the furnace which during the working period is held downby bolts or clamps is removable by elevating devices engaging with theears 6. Valve tubes 'l' containing sight glasses communicate with thefurnace interior to permit observation of the furnace interior.rIhermio-couples may be inserted into the furnace through tubes 8.

Connected to the furnace by conduits 9 and 10 is a cooler comprising aplurality of pipes 11 located in a casing 12. A circulation of coolingwater about the pipes 11 in the casing 12 is maintained by means of theinlet and outlet pipes 13 and 14.

During the period that the work is heated to carry out desiredoperations, as for example, the union of metal parts in hydrogen byfusion of metal, the valves 15 and 16 in the conduits 9 and 10 areclosed to prevent the circulation of the gas through the cooler. Afterthe work of the furnace is completed the supply of current to theresistors 2 is interrupted. To lower the temperature of the furnace thevalves 15 and 16 are opened and a blower or pump 17 is put intooperation. Ihe blower may be is circulated through the pipes 11 where itgives up heat to the cooling fluid.` Durlng this cooling or temperaturereducing period of the furnace the supply of hydrogen thereto ismaintained. When the temperature has been'lowered to a desired point,the valves 15 and 16 are closed, the furnace is opened and the workremoved. It is particularly desirable to lower the temperature rapidlyover a range of about 100o below the fusing temperature of the brazingmetal so as to stop alloying action, which, Aparticularly in the case ofsome metals, would tend to cause deterioration of the union or joint.With this in View the pump may be driven rapidly at the start and lateron at a decreased rate if a slower cooling operation is desired.

In Fig. 1 I have shown-the conduits 9 and 10 leading to and from thecooler asbeing connected at substantially diamctrically opposite pointsto the container, and for many kinds of work this is entirelysatisfactory. There arev other kinds of work, however, for which this isnot the .most advantageous arrangement, for example, in the copper`-brazing of parts which are. placed one over thc other in the containerand where. the center portion of each part is more massive than itsperipheral portion. VWhere such is the case, I find it preferable todeliver thegas from the cooler to the container at some central pointfrom which the gas ows first overthe massive portion of the work andthen over the lighter portion. To more effectively direct the cool gasbaffles of any suitable character may be employed. In

Fig. 2 is shown a construction suitable for the last-mentioned class ofwork, 1 indicates the heat-insulated container which is provided withsuitable heating means as before, and 20 a brick work foundation. 21indicates the work or parts to be brazed or otherwise treated which mayfor example,

be turbine diaphragme or wheels which are more massive vin the centerthan at the periphery. The parts may be supported within the containerin any suitable manner. 'Ihe gas from the cooler enters the container bythe conduit 10 and flows directly downward striking the work atthecenter where the mass is greatest. Where the mass is great- -est at theperiphery a conical deflector or batiie 22 is preferably employed todeflect the gas from the center toward the periphv ery. In the brickwork is a conduit 23 which is connected to the conduit 9 leading to thepump associated with the cooler.

' `Above the opening of the conduit 23 is a balile plate 24 which servesto direct the gas Afrom the center outwardly and'thus prevent itv fromshunting more or less directly from the inlet to the outlet. By the useof the means described, the parts within the container may be cooled inysuch manner as to avoid undue strains in the parts as they are cooled.Y.

I particularly wish to emphasize the fact that whereas the reducing gaswas formerly used for one purpose only, i. e. to assist in carrying outa metallurgical process, it is now used not only for that purpose, butalso to reduce the temperatureiof the furnace and of the work or chargecontained therein. It is also. to be noted that the use of said gasprevents the entrance of air to the furnace during both operations.

What I claim as new and desire'to secure byLetters Patent of the UnitedYVStates is 1. The method of carrying out metallurgical operations in anenclosed space which consists in heating a charge in said space in anon-oxidizing,atmosphere` to a working temperature, and then cooling thecharge rapidly while still closed off from vthe outside atmosphere.

2. The method of carrying out operations at high temperature in anenclosed space which comprises confining a non-oxidizing gas in saidrspace while a charge therein is subjected to a working temperature, andthereafter circulating said gas between said space and a zone maintainedat a lower perature .closed furnace which' comprises charging thefurnace', maintaining a supply of non-oxidizing gasv within the furnace,heating the furnace and its contents to a working temperature, shuttingolf the supply of heat, establishing communication between the furnaceand a cooler, and maintaining a circulation of said gas through. thecooler and furnace to cool the latter and also its charge.

5. The method of brazing which consists in heating the parts to bejoined in the presence of a non-oxidizing gas until they unite, and thencooling the parts rapidly in said gas to prevent further-alloying of themetals.

6. The method of copper brazing which consists in heating the parts-tobe joined in i" per brazing metal, and then cooling the parts rapidly insaid gas to prevent further' alloying of the copper with the metal oftherme 7. The methocl of copper lorazing which and from said coolingmeans back io `he consists in heating the parts to be joined in furnaceso as to cool the charge rapidly :luci u closed furnace lled with areducing gas thereby prevent further alloying of the 10 until the partsare united by the copper copper with the metal of the parte.

5 brazing material, shutting 0H the supply oi ln Witness whereof, l havehereunto set heat, and then circulating said gaps from my hand this 9thday of August, 1924. ,Seid furnace to an external cooling means CHRSTINSTEENSTRUP"

